1. Technical Field
The present invention relates to a travel control device for a vehicle that allows the vehicle to follow a preceding vehicle and automatically start and stop.
2. Related Art
Up to now, an automatic inter-vehicle distance maintaining control (adaptive cruise control (ACC)) system has been known in which a constant speed travel control for maintaining a set vehicle speed is performed when there is no preceding vehicle, and a following travel control for causing a vehicle to follow the preceding vehicle in a state to maintain a following inter-vehicle distance to a preceding vehicle is performed when the preceding vehicle is detected.
Recently, a system in which an applicable range of the ACC system is expanded to a low speed range (from 0 [Km/h]) to provide a congestion following function has also been known. In the ACC system having the congestion following function, the vehicle travels following the detected preceding vehicle in a state to maintain the following inter-vehicle distance to the preceding vehicle and automatically stops and starts following a stop and a start of the preceding vehicle.
However, the vehicle equipped with the ACC system having the congestion following function follows the preceding vehicle on a general road, enters an intersection, and crosses an opposite lane in the same direction as that in which the preceding vehicle crosses the opposite lane, that is, tries to turn to the right in the case of the road of left hand traffic. In such a case, even if an oncoming vehicle approaches the intersection, if the vehicle starts following the preceding vehicle, the vehicle may come in contact with the oncoming vehicle. For that reason, in the case where the vehicle follows the preceding vehicle and enters the intersection, a driver pays attention to the oncoming vehicle approaching the intersection. When the driver recognizes the oncoming vehicle approaching, the driver is required to depress a brake pedal to cancel the ACC control or the like, to thereby avoid the contact with the preceding vehicle.
In that case, it is also predicted that a delay occurs in canceling the ACC control due to a driver's depression delay of the brake pedal. As a countermeasure, for instance, Patent Literature 1 (Japanese Unexamined Patent Application Publication No. 1999 (Hei 11)-175897) discloses a technique in which when the vehicle follows the preceding vehicle and reaches a vicinity of the intersection where the vehicle is to turn to the right or left, the ACC control is automatically cancelled, and thereafter, the ACC control is resumed when the vehicle has turned to the right or left at the intersection and crossed over the intersection.
According to the technique disclosed in the literature described above, when the vehicle reaches the vicinity of the intersection, the ACC control is automatically canceled irrespective of a driver's intention. For that reason, for instance, when the vehicle is about to turn (a right turn in a left hand traffic) in the same direction as that of the preceding vehicle, the driver is required to depress the brake pedal immediately after the ACC control has been canceled or the like to adjust the inter-vehicle distance to the preceding vehicle. A high responsiveness is required immediately after the ACC control has been canceled.
In particular, in the case where the vehicle is going to turn in a direction of crossing the opposite lane at the intersection (a right turn in the left hand traffic), the driver must pay attention to not only the oncoming vehicles traveling on the opposite lane, but also pedestrians walking on a sidewalk whom the vehicle is to going to cross and bicycles trying to cross a pedestrian crossing and so on. For that reason, it is also assumed that the driver has forgotten that the ACC control has been automatically canceled.